Movable scaffold



April 8 1924.

. F. HOFFMANN MOVABLE 'scAFFoLD Filed Dec. 231

)922 3 Sheets-Sheet l OW @O w April 8 1924. Y 1,489,437

' F. HOFFMANN MOVABLE SCAFFOLD Filed Dem 23. 1922 5 sheets-sheet. 2

F. HOFFMANN MovABLE scAFFoLD April 8 1924.

Filed Dec. 23, 1922 3 Sheets-Sheet 3 lwfnmwllnl-II lll gwuanto'c 9&2; fvlctomm.

Patented Apr. 8, 19x24.

UNITED` STATES 1,489,413?v PATENT OFFICE..y

FRANK HOFFMANN, or PHILADELPHIA, PnNNsvLvANLA, AssIGNoR or ONHFORTH To THOMAS FRANcrs DURKIN, on PHILADELPHIA, PENNSYLVANIA.'

MO-VABLE SCAFFOLD.

Application md December 23, 1,922. serii No. 608380.

To all lwhom t may concern: i

Be it known that I, FRANK HOFFMANN, a citizen of the United States, residing at Philadelphia, in the county of-.Fhiladelphia and State of Pennsylvania, have invented certain new and useful Improvements in Movable Scaffolds, of which the following is a specification.

' My invention relates to movable scafolds and more particularly to scafolds used in building construction.

Heretofore scaifolds used in building construction and suspended by cables had separate mechanism for each set of cables for l5 raising and lowering the platform, thereby necessitating the manipulation of each mechanism separately.

The object of my invention is to provide a platform whereby the mechanism for raising and lowering is concentrated in one unit and to provide a unit which may be operated by one person. f

This object, and other advantageous ends which will be described hereinafter, I attain in the following manner, reference bein had to the accompanying drawings in which- Figure 1 is a top plan view of a movable platform constructed in accordance with my invention,

Figure 2 a front view of FigureV 1, and Figure 3 a section on line 3-3 of Figure 2. Referring to the drawings, a scaffold support 1 has secured thereto a hoisting unit 2 including a frame 3 in which is mounted a drum 4 having secured thereto hoisting cables 5 which pass over pulleys 6 secured to the scaffold support and may be suspended from any suitable support. The drum 4 has fixed thereto a gear 7 meshing with a gear 8 fixed to a horizontal shaft 9 mounted in the frame. Shaft 9 has xed thereto a worm Wheel 10 meshing with a worm 11 fixed to a worm shaft 12 which is mounted in bearings fixed to the frame and has xed thereto a bevel gear 13 meshing with another bevel gear 14 fixed to a stud shaft 15 mounted in bearings in the frame. Stud shaft 15 has an angular end adapted to receive a crank handle for rotating the same. To remove the strain from the worm Wheel when the scaffold is at rest, I provide ka ratchet wheel 16 co-acting with a pawl 17 to hold the drum against rotation.

When the scaffold is in use and it is desired to raise or lower the same, a. crank handle placed on the square end 115, the` crank is. turned in one .direction for raising the scaffold and in the opposite direction .for

lowering lthe scaffold.. It will beunderstood that the pawl will be out of engagement with the ratchet wheel while the scaffold is lowered. When the sca'old is at rest in the desired position, the crank is turned until a tooth of the ratchet wheel engages the pawl -and prevents the rotation of the drum, thereby removing the strain from the worm.

WhileI `have described my invention as taking a particular form, it will bel under stood that the various parts of my invention may be changed without departing from the spirit thereof, and hence I do not limit myself to the precise construction set forth, but consider that I am at liberty to make such changes and alterations as fairly come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letr ters Patent is 1. A movable scaffold including a scaffold support; pulleys mounted beneath the ends of the support; a frame secured to the sides of the support; a drum rotatable in the frame beneath the support; cables passing under the pulleys and connected to the drum; a worm shaft rotatable on theside 85 of the frame and extending above and below the support; a worm on the lower end of the shaft; means operatively connecting the worm with the drum; a stud shaft rotatable in the frame adjacent the upper end of the 9, p

worm shaft, and means operatively connecting the worm shaft with the stud shaft.

2. A movable scaffold including a scaffold v support; pulleys mounted beneath the ends of the support; a frame securedto the sides of the support; a drum rotatable in the frame beneath the support; cables passing under the pulleys and connected to the drum; a vworm shaft rotatable on the sides of the frame and extending above and below 1. the support; a worm on the lower end of the shaft; a horizontal shaft rotatable in the frame beneath the support and above the drum; a Worm wheel on the horizontal shaft meshing with the worm; means operatively 1 connecting the drum with the horizontal shaft; a stud shaft rotatable in the frame adjacent the upper end of the worm shaft, and gears operatively connecting the worm shaft with the stud shaft. p

3. A movable' scaifold lincluding 'a scaffold support;pulleys mounted beneath the'ends of the support; a frame secured to the sides of the support; a drum rotatable in the frame beneath the support; cables passing-V under the pulleys and connected to the drum; a ratchet operatively connected with the drum and the frame; a horizontal shaft rotatable in the rar'ne beneath the supportY Wormen the: lower end of the shaft meshing 15 with the Worm Wheelya-stud shaft rotatable in the frame adjacent the upper end of the VWorm shaft and extendinginward, and bevel gears 1operativelyl connecting the stud shaft with the Worm shaft.

In, testimony whereof I have signed my name to this specification in the presence of` twoA subscribing" witnesses.

' FRNK"HOFFMANN;

Witnesses 

